The present invention relates to a method for making clamping grooves around each end of lightweight pipe connectors (fittings), and relates more particularly to the method rolling grooves for a semi-finished pipe connector made of metal plate after the common steps have been taken by using a special groove rooling machine which comprises a tolling unit and a positioning unit for mass fablication.
Regular pipe connectors (fittings) are commonly made of metal by casting. The wall of a pipe connector made by casting has a certain thickness. During installation, a tapered pipe thread or an annular groove must be made at each end by cutting. However, because a pipe connector made by casting is heavy, it is not suitable for all purposes. In some cases, lightweight pipe connectors shall be used. Regular lightweight pipe connectors are commonly made by processing a metal plate into a tube, then cutting the tube thus obtained to the desired size and then processing it into a pipe connector of desired shape by hydraulic extruding and welding. Because a pipe connector made according to this method has a thin wall thickness, it cannot be processed with a tapered thread even an annular groove by this case, a rolling machine of common use may be used to make the end of the pipe connector with an annular groove. However, the working piece fixture of a common use rolling machine is not suitable for various shap of pipe connector for example an elbow or a Y-shaped connector, further more, it is difficult for centering the working piece in position.